The present invention relates generally to seat restraint systems for vehicles and, more particularly, to an acceleration sensor assembly for a restraint retractor of a seat restraint system in a vehicle.
It is known to provide a seat restraint system such as a seat belt in a vehicle to restrain an occupant in a seat of the vehicle. In some vehicles, the seat restraint system may be a lap belt, a shoulder belt or both. Typically, the lap belt and shoulder belt are connected together at one end. The seat restraint system includes a latch plate at the connected end. The seat restraint system also includes a buckle connected at one end by webbing or the like to vehicle structure. The buckle receives the latch plate to be buckled together. When the buckle and latch plate are buckled together, the seat restraint system restrains movement of the occupant to help protect the occupant during a collision.
It is also known to provide a restraint retractor for the seat restraint system. Typically, the restraint retractor has a spool attached to belt webbing of the seat restraint and is rotatably mounted to the restraint retractor by a shaft. The restraint retractor has a spiral spring on one end of the shaft to urge the spool in a direction for retracting the belt webbing when not in use. Also, the restraint retractor has a toothed locking sprocket on the other end of the shaft and a locking pawl to engage the sprocket to lock the shaft against rotation in the other direction to prevent belt webbing unwinding. The locking sprocket is typically slaved to an acceleration sprocket via a spring and an acceleration pawl is actuated by an acceleration sensing mechanism or sensor. The acceleration sensor includes a mass member or xe2x80x9cstanding manxe2x80x9d that may be spherically shaped or frusto-conical in shape to engage and actuate the acceleration pawl.
The restraint retractor is attached to the seat or vehicle body. In an xe2x80x9call belts to seatxe2x80x9d application, the restraint retractor is attached to a frame of a seat back of the seat. When the restraint retractor is attached to the seat, the acceleration sensor is sensitive and the mass member is easily activated, such as when the seat back is reclined, thereby actuating the acceleration pawl to engage the acceleration sprocket and operatively causing the locking sprocket and locking pawl to engage via the spring to lock the shaft of the restraint retractor against rotation. This condition is undesired.
Therefore, it is desirable to provide an acceleration sensor for a restraint retractor of a seat restraint system in a vehicle that is de-sensitized. It is also desirable to provide an acceleration sensor for a restraint retractor of a seat restraint system in a vehicle that eliminates noise. It is further desirable to provide an acceleration sensor for a restraint retractor of a seat restraint system in a vehicle that has the ability to allow acceleration sensing.
It is, therefore, one object of the present invention to provide an acceleration sensor assembly for a restraint retractor of a seat restraint system in a vehicle that is de-sensitized.
It is another object of the present invention to provide an acceleration sensor assembly for a restraint retractor of a seat restraint system in a vehicle that eliminates noise.
To achieve the foregoing objects, the present invention is an acceleration sensor assembly for a restraint retractor of a seat restraint system including an acceleration sprocket operatively connected to the restraint retractor. The acceleration sensor assembly also includes an acceleration pawl cooperating with the sprocket to lock up the restraint retractor. The acceleration sensor assembly includes a mass member cooperating with the locking member to move the locking pawl when an acceleration force is present. The acceleration sensor assembly further includes an electromagnet assembly cooperating with the mass member to hold the mass member in a predetermined position until the force exceeds a predetermined value. The mass member moves to actuate the locking pawl to engage the sprocket to lock up the restraint retractor and prevent unwinding of a belt from the restraint retractor.
One advantage of the present invention is that an acceleration sensor assembly is provided for a restraint retractor of a seat restraint system in a vehicle. Another advantage of the present invention is that the acceleration sensor assembly eliminates noise for a seat restraint system in a vehicle. Yet another advantage of the present invention is that the acceleration sensor assembly changes the xe2x80x9cGxe2x80x9d level and allows the restraint retractor to operate with high xe2x80x9cGxe2x80x9d accelerations or decelerations. Still another advantage of the present invention is that the acceleration sensor assembly senses in three hundred sixty degrees of horizontal plane and not only in a fore-aft direction.
Other objects, features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings.